Year 9 Science · Unit 3 · Lesson 1

Introduction to Energy

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Learning Goals

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Real-world context

Australia's National Electricity Market (NEM) connects power stations in Queensland, New South Wales, Victoria, South Australia, and Tasmania to millions of homes. The largest power stations burn black or brown coal to generate electricity. When electricity reaches your home, it powers everyday devices, including the humble electric fan that keeps you cool on a hot summer afternoon.

(a) Trace the energy transformations from burning coal to a spinning fan in your home. List at least four stages in your answer.

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(b) At each stage, some energy becomes heat that spreads into the surroundings. Using what you know about conservation of energy, explain whether this heat energy is "lost".

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Because… chain

The boxes on the left show a stage in the coal-to-fan energy chain. Fill in each right-hand box with the energy form that results at that stage. Then write the overall outcome at the bottom.

Chemical energy stored in coal
Combustion heats water to steam
Steam drives turbine blades to spin
Generator converts spin to electricity
Electricity flows through wires to your home
Electric motor in fan spins the blades

Overall outcome: the original chemical energy in coal has become…

1. Explain the difference between an energy transfer and an energy transformation. Use one example of each from the coal-to-fan chain above.

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2. Australia uses approximately 6,000 petajoules (PJ) of energy per year. Suggest TWO reasons why understanding energy transformations matters for planning how Australia meets this demand.

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Wrap Up

In one sentence, what was the main idea of this lesson?